Automatic xy centering for digital microscope

ABSTRACT

A method and system are described for automatically centering in an XY plane a field of view of a patient&#39;s eye under high magnification during ophthalmic surgery. The method includes automatically moving the center of the field of view to the center of a circular image detected in a real-time video signal acquired from the field of view of the patient&#39;s eye under high magnification during ophthalmic surgery. The system configured to perform the method has a processor and a non-transitory computer-readable medium accessible to the processor containing instructions executable by the processor to perform the method.

BACKGROUND

The present disclosure relates to ophthalmic surgery, and morespecifically, to a method and system configured to allow automaticcentering in an XY plane a field of view of a patient's eye under highmagnification during ophthalmic surgery.

In ophthalmology, ophthalmic surgery saves and improves the vision oftens of thousands of patients every year. However, given the sensitivityof vision to even small changes in the eye and the minute and delicatenature of many eye structures, ophthalmic surgery is difficult toperform and the reduction of even minor or uncommon surgical errors ormodest improvements in accuracy of surgical techniques can make anenormous difference in the patient's vision after the surgery.

During ophthalmic surgery, surgeons use a microscope to magnifyvisualization of a patient's eye or a part of the eye that is beingoperated on. During ophthalmic surgery, surgeons may use eyepieces,otherwise known as oculars, to view the eye or part thereof that isbeing magnified by the microscope. Alternatively, or in addition, duringophthalmic surgery, an image of the eye or part thereof that ismagnified by the microscope may be displayed on a screen viewable by thesurgeon and other personnel in an operating room. However, improvementsin control of the display of the magnified image on the screen duringophthalmic surgery remains challenging.

SUMMARY

The present disclosure provides a system configured for automaticallycentering in an XY plane a field of view of a patient's eye under highmagnification during ophthalmic surgery. The system includes aprocessor; and a non-transitory computer-readable medium accessible tothe processor containing instructions executable by the processor for:acquiring, from a photosensor, a real-time video signal representing afield of view including the patient's eye under high magnification by amicroscope, wherein the field of view includes an en-face XY plane;displaying on a display at least one view within the field of viewcorresponding to the real-time video signal; detecting a circular imagein the real-time video signal, wherein the circular image includes atarget image in the field of view; determining the location of thecenter of the circular image within the XY plane of the field of view;determining the location of the center of the field of view in the XYplane; comparing the location of the center of the circular image andthe location of the center of the field of view; upon determining adifference in the locations of the center of the circular image and thecenter of the field of view, transmitting a movement instruction to amotorized microscope support configured to move the location of themicroscope field of view in the XY plane, wherein the movementinstruction directs movement of the microscope field of view to placethe center of the field of view at the location of the center of thecircular image; thereby automatically moving the center of the field ofview to the center of the circular image detected in the real-time videosignal acquired from the field of view of the patient's eye under highmagnification during ophthalmic surgery.

The present disclosure also provides a method of automatically centeringin an XY plane a field of view of a patient's eye under highmagnification during ophthalmic surgery. The method includes the stepsof: acquiring, by a processor executing instructions contained in anon-transitory computer-readable medium, from a photosensor, a real-timevideo signal representing a field of view including the patient's eyeunder high magnification by a microscope, wherein the field of viewincludes an en-face XY plane; displaying on a display, via the processorexecuting instructions contained in the non-transitory computer-readablemedium, at least one view within the field of view corresponding to thereal-time video signal; detecting a circular image in the real-timevideo signal, by the processor executing instructions contained in thenon-transitory computer-readable medium, wherein the circular imageincludes a target image in the field of view; determining, by theprocessor executing instructions contained in the non-transitorycomputer-readable medium, the location of the center of the circularimage within the XY plane of the field of view; determining, by theprocessor executing instructions contained in the non-transitorycomputer-readable medium, the location of the center of the field ofview in the XY plane; comparing, by the processor executing instructionscontained in the non-transitory computer-readable medium, the locationof the center of the circular image and the location of the center ofthe field of view; and, upon determining a difference in the locationsof the center of the circular image and the center of the field of view,transmitting, by the processor executing instructions contained in thenon-transitory computer-readable memory, a movement instruction to amotorized microscope support configured to move the location of themicroscope field of view in the XY plane, wherein the movementinstruction directs movement of the microscope field of view to placethe center of the field of view at the location of the center of thecircular image; thereby automatically moving the center of the field ofview to the center of the circular image detected in the real-time videosignal acquired from the field of view of the patient's eye under highmagnification during ophthalmic surgery.

In any of the disclosed implementations, the system and method mayfurther include the following details:

i) the center of the field of view may correspond to a set location onthe display;

ii) the set location on the display may be the center of the display;

iii) the display may be a rectangular display and the set location onthe display may be a location at a mid-point between the long sides ofthe rectangular display;

iv) the circular image may correspond to an illuminated portion of theinside of the patient's eye viewable through a pupil of the eye;

v) the movement instructions transmitted to the motorized microscopehead support may include a parameter of velocity, wherein the value ofthe velocity is variable as a function of distance between the locationof the center of the field of view and the center of the circular image;

vi) the value of the velocity of the movement instructions may increasewith increasing distance between the location of the center of the fieldof view and the center of the circular image;

vii) the value of the velocity of the movement instructions may increaselinearly;

viii) the value of the velocity of the movement instructions mayincrease non-linearly;

ix) the magnification may have a zoom having a value; and the displaymay have an area; wherein the method further includes: detecting, by theprocessor, executing instructions contained in the non-transitorycomputer-readable medium, a diameter of the circular image;transmitting, by the processor, executing instructions contained in thenon-transitory-computer-readable medium, an instruction to adjust thevalue of the zoom of the magnification so that the diameter of thedetected circular image is fitted within a maximal portion of the areaof the display; wherein the transmitting of the instruction to adjustthe value of the zoom is selected from (a) transmitting an instructionto the microscope to adjust an optical zoom of the field of view of themicroscope; and (b) transmitting an instruction to the display to adjusta digital zoom of the field of view of the real-time video signal;

x) the instructions contained in the non-transitory computer readablemedium executed by the processor for the detecting of the circular imagemay include a circle Hough transform algorithm;

xi) the ophthalmic surgery may include a vitreoretinal surgery;

xii) the real-time video signal may be a 3D video signal; and

xiii) the system may include an NGENUITY® 3D Visualization System.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, referenceis now made to the following description, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 shows an exemplary schematic showing a side view of an eyeundergoing a vitreoretinal surgical procedure;

FIG. 2 shows a schematic showing an exemplary top-down view,corresponding to the en face view, of an eye undergoing an exemplaryvitreoretinal surgical procedure;

FIG. 3 shows a schematic of an exemplary system configured for automaticcentering of the XY position of a circle detected in a magnified imageof an eye by a digital microscope during ophthalmic surgery;

FIG. 4 A shows an exemplary schematic of an XY plane overlaid on acircle detected in an image of an eye under magnification duringophthalmic surgery;

FIG. 4 B shows another exemplary schematic of an XY plane overlaid on acircle detected in an image of an eye under magnification duringophthalmic surgery;

FIG. 4 C shows yet another exemplary schematic of an XY plane overlaidon a circle detected in an image of an eye under magnification duringophthalmic surgery;

FIG. 5 shows a schematic of an exemplary detected circle positioned atthe center of the vertical extent of an exemplary display;

FIG. 6 shows a schematic illustrating an exemplary circular shape in animage; and

FIG. 7 shows a schematic illustrating an exemplary image related to acircle Hough transform.

DETAILED DESCRIPTION

In the following description, details are set forth by way of example tofacilitate discussion of the disclosed subject matter. It should beapparent to a person of ordinary skill in the art, however, that thedisclosed implementations are exemplary and not exhaustive of allpossible implementations.

The present disclosure relates to ophthalmic surgery, and morespecifically, to a method to allow automatic centering in an XY plane afield of view of a patient's eye under high magnification duringophthalmic surgery, and a system configured to perform the method.

Ophthalmic surgery is performed on the eye and accessory visualstructures. For example, vitreoretinal surgery encompasses variousdelicate procedures involving internal portions of the eye, such as thevitreous humor and the retina. The retina is a light-sensitive area thatincludes the macula, which is made up of light-sensitive cells thatprovide sharp, detailed vision. The vitreous humor of the eye is a cleargel that fills the space between the retina and the lens. The retina,the macula, and the vitreous body can all be subject to various diseasesand conditions that can lead to blindness or vision loss and may requirethe attention of a vitreoretinal surgeon.

Different vitreoretinal surgical procedures are used, sometimes withlasers, to improve visual sensory performance in the treatment of manyeye diseases, including epimacular membranes, diabetic retinopathy,vitreous hemorrhage, macular hole, detached retina, and complications ofcataract surgery, among others.

Ophthalmic surgery often involves removal of eye tissue. For example,cataract surgery generally requires the removal and replacement of thelens. An artificial lens or intraocular lens implant can then beimplanted within the eye to restore or improve the eyesight of thepatient. Other procedures may also involve the removal of lens tissueand/or other types of eye tissue.

There are a number of procedures and devices that have been developedfor the removal of eye tissue. For example, phacoemulsification is awidely used method for removal of diseased or damaged lens tissue. Thephacoemulsification process generally involves insertion of a probethrough a small corneal incision to break apart and remove the lens incataract surgery.

In phacoemulsification, one or more incisions are generally made in theeye to allow the introduction of surgical instruments. The surgeon thenremoves the anterior face of the capsule that contains the lens insidethe eye. An ultrasonic handpiece, where the tip vibrates at ultrasonicfrequency, is generally used to sculpt and emulsify the cataract. Afterremoval of the cataract, the posterior capsule is generally still intactand an intraocular lens implant (IOL) can be placed into the remaininglens capsule.

During ophthalmic surgery, because of the small size and delicate natureof the eye structures, surgeons typically use a microscope to magnifyvisualization of a patient's eye or a part of the eye that is beingoperated on. Typically, in the past, during ophthalmic surgery, surgeonsused eyepieces, otherwise known as oculars, to view the eye or partthereof that is being magnified by the microscope. During ophthalmicsurgery, stereo microscopes having two eyepieces viewable by both eyessimultaneously for binocular view are typically used. Some ophthalmicsurgery procedures can take several hours to perform, and thereforepreviously, during ophthalmic surgery, ophthalmic surgeons would oftenbe required to look through the binocular eyepieces of their microscopesfor hours on end.

More recently, as an alternative to using eyepieces, or in addition,during ophthalmic surgery, developments in digital microscopy haveallowed an image of the eye or part thereof that is magnified by themicroscope to be displayed on a screen viewable by the surgeon and otherpersonnel in an operating room. Among the benefits of using a displayscreen, rather than using microscope oculars, to visualize eyestructures during ophthalmic surgery include decreased fatigue andincreased comfort for the surgeon. In addition, unlike microscopesoculars, because the display can be viewed by more than one person at atime, the use of a display is useful for teaching and improvescommunication regarding the surgical procedure between personnel in theoperating room.

Ophthalmic surgery visualization platforms utilizing digital microscopyand display screens applicable to the method and systems describedherein generally include at least one high resolution photosensor suchas a camera or charge coupled device (CCD) which is capable of receivingand acquiring a plurality of optical views of an eye under magnificationby a microscope. Those skilled in the art will appreciate that receivinglight in visible wavelengths in addition to wavelengths outside of thewavelengths of normal visible light is also within the scope of thepresent invention. In general, the high resolution photosensor thentransmits a resultant real-time high-resolution video signal which istransmitted, via a processor executing instructions contained in anon-transitory computer readable medium, to at least one high resolutionvideo display. In some configurations, because of the multiple highresolution optical views transmitted and presented on the display, theoperator of the visualization platform, or others, is able to view areal-time high definition three-dimensional visual image of the targetobject or tissue.

Exemplary real-time visualization platforms suitable for implementingthe system and practicing the methods described herein include thosedescribed U.S. Pat. Nos. 9,168,173, 8,339,447, and 8,358,330, all ofwhich are incorporated herein by reference.

The term “display” as used herein refer to any device capable ofdisplaying a still or video image. Preferably, the displays of thepresent disclosure display high definition (HD) still images and videoimages or videos which provide a surgeon with a greater level of detailthan a standard definition (SD) signal. More preferably, the displayspresent such HD stills and images in three dimensions (3D). Exemplarydisplays include HD monitors, cathode ray tubes, projection screens,liquid crystal displays, organic light emitting diode displays, plasmadisplay panels, light emitting diodes (LED) or organic LED (OLED), 3Dequivalents thereof and the like. 3D HD holographic display systems areconsidered to be within the scope of the present disclosure.

The visualization platforms described herein include at least one highresolution photosensor. A photosensor is an electromagnetic sensor thatresponds to light and produces or converts it to an electrical signalwhich can be transmitted to a receiver for signal processing or otheroperations and ultimately read by an instrument or an observer. It maybe capable of responding to or detecting any or all of the wavelengthsof light that form the electromagnetic spectrum. Alternatively, thephotosensor may be sensitive to a more restricted range of wavelengthsincluding the at least one wavelength of light outside of thewavelengths of visible light.

An example of a photosensor which the visualization platforms describedherein can include is a camera. A camera is a device used to captureimages, either as still photographs or as sequences of moving images(movies or videos). A camera generally consists of an enclosed hollowwith an opening (aperture) at one end for light to enter, and arecording or viewing surface for capturing the light at the other end.The recording surface can be chemical, as with film, or electronic.Cameras can have a lens positioned in front of the camera's opening togather the incoming light and focus all or part of the image on therecording surface. The diameter of the aperture is often controlled by adiaphragm mechanism, but alternatively, where appropriate, cameras havea fixed-size aperture.

Exemplary electronic photosensors in accordance with the presentdisclosure include, but are not limited to, complementarymetal-oxide-semiconductor (CMOS) sensors or charge-coupled device (CCD)sensors. Both types of sensors perform the function of capturing lightand converting it into electrical signals. A CCD is an analog device.When light strikes the CCD it is held as a small electrical charge. Thecharges are converted to voltage one pixel at a time as they are readfrom the CCD. A CMOS chip is a type of active pixel sensor made usingthe CMOS semiconductor process. Electronic circuitry generally locatednext to each photosensor converts the received light energy into anelectrical voltage and additional circuitry then converts the voltage todigital data which can be transmitted or recorded.

The real-time high-resolution video signal transmitted can be a digitalvideo signal which is a digital representation of discrete-time signals.Often times, digital signals are derived from analog signals. As wouldbe understood by persons skilled in the art, a discrete-time signal is asampled version of an analog signal where the value of the datum isnoted at fixed intervals (for example, every microsecond) rather thannoted continuously. Where the individual time values of thediscrete-time signal, instead of being measured precisely (which wouldrequire an infinite number of digits), are approximated to a certainprecision—which, therefore, only requires a specific number ofdigits—then the resultant data stream is termed a “digital” signal. Theprocess of approximating the precise value within a fixed number ofdigits, or bits, is called quantization. Thus, a digital signal is aquantized discrete-time signal, which in turn is a sampled analogsignal. Digital signals can be represented as binary numbers, so theirprecision of quantization is measured in bits.

It will be appreciated by those of ordinary skill in the art that byattaching a photosensor to a visualization device such as astereomicroscope which directs a plurality of views of a target objectonto the photosensor the visualization systems described herein are ableto acquire a plurality of optical views of a target object, such as amagnified eye during ophthalmic surgery, and transmit that informationas a real-time high resolution video signal that can be recorded orpresented for display and viewing. In some implementations, thetransmitted digital video signal is capable of producing an image havinga resolution of at least about 1280 lines by 720 lines. This resolutioncorresponds to the typically minimum resolution for what one of ordinaryskill in the art would consider to be high definition or an HD signal.

“Real-time” as used herein generally refers to the updating ofinformation at the same rate as data is received. More specifically, inthe context of the present invention “real-time” means that the imagedata is acquired, processed, and transmitted from the photosensor at ahigh enough data rate and a low enough delay that when the data isdisplayed objects move smoothly without user-noticeable judder orlatency. Typically, this occurs when new images are acquired, processed,and transmitted at a rate of at least about 30 frames per second (fps)and displayed at about 60 fps and when the combined processing of thevideo signal has no more than about 1/30^(th) second of delay.

When the high resolution video signal is received and presented on avideo display having corresponding high resolution or HD capabilitiesthe resultant image provides a degree of clarity, detail, and controlpreviously unattainable in the absence of high ambient visual light.Exemplary visual displays include cathode ray tubes, projection screens,liquid crystal displays, organic light emitting diode displays, plasmadisplay panels and light emitting diode displays.

When the real-time high resolution video signal described hereinincludes multiple views of the target object or tissue the video displaycan be made three dimensional (“3D”) so that depth of field is presentedto the ophthalmic surgeon. Exemplary types of high resolution 3D videodisplays include stereoscopic 3D displays using polarized glasses suchas those developed by TrueVision Systems, Inc. Alternatively,autostereoscopic 3D displays that do not require the use of any specialglasses or other head gear to direct different images to each eye can beused. Similarly, holographic 3D displays are also contemplated as beingwithin the scope of the present disclosure.

Examples of systems for digital microscopy that utilizes display screensfor visualization during ophthalmic surgery include Alcon LaboratoriesNGENUITY® 3D Visualization System (Alcon, Inc. Corporation Switzerland,Hunenberg Switzerland), a platform for Digitally Assisted VitreoretinalSurgery (DAVS). In particular, the NGENUITY® system is designed toenhance visualization of the back of the eye for improved surgeonexperience. The NGENUITY® system refers to a system developed incollaboration with TrueVision® 3D Surgical (TrueVision Systems, Inc.Goleta Calif.). The NGENUITY® 3D Visualization System allows retinalsurgeons to operate looking at a high definition 3D screen, instead ofbending their necks to look through the eye-piece of a microscope.Traditional vitrectomy surgeries range from 30 minutes to over threehours in length to complete. This microscope eyepiece-free design isengineered to improve surgeons' posture and may reduce fatigue.

The NGENUITY® 3D Visualization System includes several elements,including a High Dynamic Range (HDR) camera that provides highresolution, image depth, clarity and color contrast. The HRD is a 3Dstereoscopic, high-definition digital video camera configured to providemagnified stereoscopic images of objects during micro-surgery. The videocamera functions as an addition to the surgical microscope duringsurgery and may be used to display real-time images or images fromrecordings. In particular, with the three-dimensional view, the surgeonhas depth perception not previously available on standard televisionmonitors. Surgeons may also increase magnification while maintaining awide field of view as well as using digital filters to customize theirview during each procedure, highlighting ocular structures and tissuelayers which is imperative to visualize the back of the eye. Engineeredwith a specific focus on minimizing light exposure to the patient's eye,the NGENUITY® 3D Visualization System facilitates operating using lowerlight levels (Eckardt C and Paulo EB. Heads-up surgery for vitreoretinalprocedures: An Experimental and Clinical Study. Retina. 2016 January;36(1):137-47).

Despite the advantages described herein of displaying the magnifiedimage on the screen during ophthalmic surgery, improvement in control ofthe display of the magnified image on the screen during ophthalmicsurgery remains challenging.

For example, high magnification is needed to utilize the entire extentof the display, such as an NGENUITY® 55 inch OLED display at a distance,e.g., 4-6 feet, from the surgeon. During surgery, the position of theeye, or a portion of the eye that the surgeon intends to view, may moverelative to the position of the microscope field of view in an XY planecorresponding to an en-face field of view. Movement may be due tomovement of the patient during surgery, or movements associated withmanipulation of the eye tissue during surgery. Accordingly, in order tomaintain the portion of the eye that the surgeon intends to view in thefield of view of the microscope, the position of the microscope in theXY plane must be reoriented so that the microscope's field of view isrealigned with the position of the portion of the eye that the surgeonintends to view. In particular, the high magnification used duringsurgery means that even small movements during surgery may correspond tomovement of the portion of the eye that the surgeon intends to viewrelative to the microscope's field of view, and as a result, movement ofthe real-time video image off the display screen. This can have theresult that the surgeon is not able to effectively visualize the portionof the eye that the surgeon intends to view on the display screen.

Currently, centering of the magnified real-time video image on thescreen is typically performed by manual control, such as manualoperation of a foot switch joystick to drive XY motors in a box betweena microscope support arm and the microscope head. In particular, veryfrequent surgeon control of the XY position on the microscope isrequired because of high magnification. In addition, manual control ofthe position of the magnified circular video image can be imprecise andproblematic. For example, manual control may lead to sub-optimalcentering of the image on the screen, or the real-time video image beingpositioned off-screen. In addition, manual control, such as using a footswitch joystick, can cause inadvertent motion of the surgeon's handduring surgery.

Given the need for fine-tuned control during ophthalmic surgery,improvements in equipment used by an ophthalmic surgeon to provideincreased control over surgical techniques is expected to improvesurgical outcomes for the patient.

The present disclosure generally relates to automatic centering of themagnified video image of the patient's eye on the screen viewed by thesurgeon during ophthalmic surgery.

The term “high magnification” as used herein may refer to any value orrange of magnification that may be typically used during ophthalmicsurgery, such as vitreoretinal surgery, identifiable by skilled persons.For example, in some implementations, an exemplary high magnificationmay refer to a magnification value within a range of about 2× to 100×,or about 10× to 40×, or about 10× to 20×, among other rangesidentifiable by skilled persons. In some implementations, highmagnification may refer to a magnification value of about 20×.

Exemplary surgical microscopes that may be used with the system andmethod described herein include the Zeiss OPMI® Lumera T (Carl ZeissCorporation, Germany), among other identifiable by persons skilled inthe art. As would be understood by skilled persons, suitable microscopesmay feature a magnification range, for example of approximately3.5×-21.0× at a working distance of 200 mm, a motorized zoom systemhaving a suitable zoom ratio such as 1:6 zoom ratio, a magnificationfactor γ, for example of approximately 0.4 to 2.4, and a focusing rangeof approximately 50 mm.

The total magnification of the system may be calculated by skilledpersons by taking into account factors of the microscope and thephotosensor, such as the focal length, the magnification factor set onthe zoom components of the system, and the magnification factor of thephotosensor, among other factors identifiable by skilled persons.

Methods and systems that include components having optical and/ordigital zoom capability are contemplated in the present disclosure.

In general, it is understood that the term “automatic” refers to anaction or a process that does not require manual control or manipulationby a user, such as an ophthalmic surgeon.

In particular, the term “automatic centering”, as used herein inrelation to a high magnification image of a patient's eye, refers to thecontrol of centering of a magnified field of view that is performed bymeans of a computer processor executing instructions contained within anon-transitory computer-readable medium, as described herein.

In general, described herein is a method and system that utilizes videoanalysis software that detects a circle or an approximately circularimage in a real-time video of a patient's eye during ophthalmic surgeryand, in response, drives movement of the microscope's field of view XYposition so the corresponding high magnification circular video image iscentered on the display screen.

As would be understood by skilled persons, with regard to the detectionof magnified images of eyes and structures within eyes during ophthalmicsurgery, the term “circle” as used herein refers to an approximatelycircular shape and may include ellipses and approximately ellipticalshapes.

In particular, the automatic XY image centering method and systemdescribed herein are useful for ophthalmic surgical procedures such asvitreoretinal surgery.

For example, FIG. 1 shows an exemplary schematic 100 showing a side viewof an eye undergoing a vitreoretinal surgical procedure. Indicated inthe schematic diagram are various tools inserted into the eye throughincisions, including a vitrector cutting device 101 that removes theeye's vitreous gel in a slow, controlled fashion. Also shown is acannula 102, used to replace fluid in the eye with a saline solution andto maintain proper eye pressure. Also shown is a light pipe 103, whichprovides illumination inside the eye. During a vitreoretinal surgery,such as shown in exemplary schematic diagram in FIG. 1, the ophthalmicsurgeon visualizes the illuminated portion of the retina 104 using amicroscope directed to view the internal part of the eye through thepupil 105.

FIG. 2 shows a schematic 200 showing an exemplary top-down view,corresponding to the en face view, of an eye undergoing an exemplaryvitreoretinal surgical procedure, similar to the exemplary procedureshown in side-view in FIG. 1. Indicated in the schematic diagram arevarious tools inserted into the eye through incisions, including avitrector cutting device 201, a cannula 202, and a light pipe 203, whichprovides illumination inside the eye. During a vitreoretinal surgery,such as shown in exemplary schematic diagram in FIG. 2, the ophthalmicsurgeon visualizes the illuminated portion of the retina 204 using amicroscope directed to view the internal part of the eye through thepupil, the outline of which is shown as a dashed circle 205.

During vitreoretinal surgery, for example, the field of view of thesurgical microscope is often limited to a minute fraction of the wholeretina. Typically, this minute fraction appears on the live real-timevideo image as a small patch of the retina on a predominantly darkbackground. The shape of the patch viewable by the ophthalmic surgeonvia the microscope is determined by the shape of the pupil, which isusually a circular or elliptical disk. For example, the image may beelliptical when the retinal view is through an elliptical pupil of aneye rotated up, down, left, or right. Also, in some cases, the shape ofthe patch may include variations from a circular image according tovariations in the shape of the iris of the eye, for example if the irisis absent, or part of the structure of the iris is absent or forexample, if prior surgery has altered the shape of the iris. Theilluminated portion of the image of the eye may be referred to as the“target image” that the ophthalmic surgeon intends to view on a displayduring the surgical procedure. During surgery, the position of theilluminated patch may move relative to the position of the microscopefield of view in an XY plane corresponding to the en-face field of view.Movement of the approximately circular illuminated patch may be due tomovement of the patient during surgery, or movements associated withmanipulation of the eye tissue during surgery. Accordingly, in order tomaintain the image of the approximately circular illuminated patch inthe field of view of the microscope, the position of the microscope inthe XY plane must be reoriented so that the microscope's field of viewis realigned with the position of the illuminated patch in the eye. Inparticular, the high magnification used during surgery means that evensmall movements during surgery may correspond to movement of theilluminated patch of the eye relative to the microscope's field of view,and as a result, movement of the real-time video image relative to thecenter of the display. This can have the result that the surgeon is notable to effectively visualize the illuminated patch of the eye on thedisplay screen. As described herein, currently, this requires manualrepositioning of the microscope's field of view, which has disadvantagesas described herein. To solve this problem, the methods and systemsdescribed herein allow automatic centering of the image of the magnifiedeye on the display screen. As would be understood by skilled persons,the system and method of the present disclosure is suitable forophthalmic surgery procedures that use endoillumination, wherein theterm “endoillumination” as used herein refers to the illumination of theinterior of the eye, as described herein and shown in the exemplaryschematics in FIGS. 1 and 2. When using endoillumination, externalmicroscopy illumination light sources, such as a microscope light sourceexternal to the eye, are turned off, so that the illuminated interiorportion of the eye viewable as a circular or elliptical shape throughthe pupil of the endoilluminated eye is contrasted against apredominantly dark, non-illuminated exterior portion of theendoilluminated eye. For example, when using the exemplary NGENUITY® 3DVisualization System for performing vitreoretinal surgery, the interiorof the eye is visualized by endoillumination, and external microscopelight sources are turned off.

The term “XY plane” as used herein refers to the 2-dimensional spacedefined by an X axis and a Y axis, wherein the X axis is perpendicularto the Y-axis and the X axis and the Y axis intersect at a pointreferred to as the origin.

In particular, as used herein, the XY plane may refer to a plane that istypically approximately parallel to the ground, or the floor of theoperating room, and in particular may form a plane that is approximatelyhorizontal above the eye during ophthalmic surgery, while the patient islying down, face up on an operating table. Thus, for example, the term Xaxis as used herein may refer to a horizontal axis that is orientedleft-right relative to the position of the ophthalmic surgeon, and forexample the term Y axis as used herein may refer to a horizontal axisthat is oriented forward-backward (or distal-proximal) relative to theposition of the ophthalmic surgeon. With respect to the field of view ofthe eye viewable through the microscope and the corresponding real-timevideo image that represents the field of view, the XY plane correspondsto the 2-dimensional space of the en-face view of the real-time videoimage. In some implementations, the real-time video signal is a 3D videosignal, wherein in addition to the 2-dimensions of the en-face XY plane,the video signal also contains video data corresponding to the depth ofthe field of view in the Z axis, which is perpendicular to the XY plane.

It is understood that the XY plane may form a coordinate grid, wherein acoordinate refers to a position in the XY plane that is defined by theintersection of a value on the X axis and a value on the Y axis, whereinthe values indicate a distance from the origin, wherein the origin maybe nominally indicated by coordinates of X=0 and Y=0. Skilled personswill understand that XY coordinates generally relate to the Cartesiancoordinate system, which is a system in which the location of a point isgiven by coordinates that represent its distances from perpendicularlines that intersect at a point called the origin. A Cartesiancoordinate system in a plane has two perpendicular lines (the X-axis andY-axis); in three-dimensional space, it has three (the X-axis, Y-axis,and Z-axis).

FIG. 3 shows a schematic of an exemplary system 300 configured forautomatic centering of the XY position of a circle detected in amagnified image of an eye by a digital microscope during ophthalmicsurgery. It is to be understood that the system 300 configured forautomatic centering of the XY position of a circle detected in amagnified image of an eye by a digital microscope during ophthalmicsurgery shown in FIG. 3 is exemplary and non-limiting, and that otherconfigurations of the system 300 that are operative within the scope ofthe present disclosure are identifiable by persons skilled in the art.Modifications, additions, or omissions may be made to the system 300without departing from the scope of the disclosure. The components andelements of the system 300, as described herein, may be integrated orseparated according to particular applications. The system 300 may beimplemented using more, fewer, or different components in someimplementations.

FIG. 3 shows an eye 301 with pupil 302. A microscope 303 is shown,wherein an exemplary field of view 304 of the microscope 303 is shown asbounded by dashed lines. An XY plane 305 formed by an X axis and a Yaxis, respectively indicated by arrows 317 and 318 is shown horizontallyabove the eye 301 and below the microscope 303. The microscope 303 isconfigured to be in electronic communication with a photosensor such asa camera 306 via an electronic connection 307 configured to allow themagnified image of the eye by the microscope 303 to be captured by thecamera 306. In particular, the camera 306 is a video camera, such as ahigh definition video camera capable of capturing images at a high framerate. The camera 306 is configured to be connected to and in electroniccommunication with a processor 308 via connection 309. The processor 308is configured to execute instructions contained in a non-transitorycomputer readable medium 310 to receive digital real-time video imagedata from the camera 306 and transmit the real-time video image displaydata to a display 311. In FIG. 3, the display 311 is shown with acircular magnified image 312 detected in an image of a portion of an eyeduring ophthalmic surgery. For example, the circular image shown on thedisplay may in some implementations be a circular or elliptical image ofan illuminated portion of a retina visible to the microscope field ofview through the pupil 302 of the eye 301 during vitreoretinal surgery.The processor 308 is in electronic communication with the non-transitorycomputer readable medium 310 via connection 313, and the processor 308is in electronic communication with the display 311 via connection 314.The processor 308 is configured to execute instructions contained in thenon-transitory computer-readable medium 310 to detect a circle in thedigital image data received from the camera 306. A motorized microscopehead support 315 is configured to move the microscope horizontallyaccording to coordinates of the XY plane 305, in order to adjust thefield of view of the microscope in the XY plane. Movement of themicroscope via the motorized microscope head support 315 is controlledby the processor 308 executing instructions from the non-transitorycomputer readable medium 310. In particular, upon detection of acircular image in the digital real-time video image data of themagnified image of the eye, the processor 308, executing instructionscontained in the non-transitory computer readable medium 310, isconfigured to send movement instructions to the motorized microscopehead support 315 to position the center of the circular image in thecenter of the field of view 304 of the microscope 303. Accordingly, theprocessor 308, executing instructions contained in the non-transitorycomputer readable medium 310, transmits movement instructions to themotorized microscope head support 315 according to the XY plane toresult in positioning the center of the circular image in the center ofthe display 311. Movement of the microscope 303 by the motorizedmicroscope head support 315 is via connection 316.

The exemplary system shown in FIG. 3 may additionally include a controlpanel (not shown) having user operated controls that allow a surgeon toadjust the characteristics of the image data such as the magnificationzoom, color, luminosity, contrast, brightness, or the like sent to thedisplay 311.

FIG. 4 A shows an exemplary schematic 400 of an XY plane 403 overlaid ona circle 401 detected in an image of an eye under magnification duringophthalmic surgery. For example, the circle 401 detected may be anilluminated internal portion of the eye viewable through the circularshape of the pupil, as depicted by the dashed circle 205 in FIG. 2. Thecircle 401 has a circle center 402 depicted as a solid black spot. TheXY plane 403 indicates the area of the field of view of the microscope,and in particular the area of the field of view of the magnified imagecaptured by the camera. The XY plane 403 formed by X axis 404 and Y axis405 has a grid of XY coordinates. The XY plane is depicted as a grid ofintersecting lines at points along the axes, however it is to beunderstood that the XY plane 403 forms a continuous horizontal planefield, so that the XY coordinates can have any X and Y values along theX and Y axes. The field of view may have any shape, such as a circle ora square. In an exemplary implementation, the field of view produced bythe microscope and NGENUITY® optical system field stops is circular. Inthe exemplary schematic shown in FIG. 4 A, the XY plane 403 indicates ahorizontal plane overlaid onto a field of view of a microscope used tovisualize an eye under magnification during ophthalmic surgery. In FIG.4 A, the field of view has a field of view center 406 indicated by asmall circle. The center of the field of view center 406 is located atthe XY coordinates intersected by lines 407 and 408, which havecoordinate values of X₀ and Y₀, respectively. In some implementations,the field of view center 406 can be a single point located at the centerof the field of view, whereas in other implementations, the field ofview center 406 can be a region having an area, such as a circular area,or any other suitable shape that defines a center region of the field ofview. In some implementations, the field of view center 406 may be aregion having a set size relative to the total field of view, such as1%, 5%, 10% or 20% of the total field of view. The circle center has XYcoordinates having coordinate values of X₁ and Y₁, respectively. In FIG.4 A, the circle center 402 is shown located in the same position as thecenter of the field of view center 406. When the circle center 402 islocated in the same position as the field of view center 406, there isno difference between the coordinates of the circle center 402 and thefield of view center 406, thus the absolute value of X₁−X₀=0 and theabsolute value of Y₁−Y₀=0.

In contrast with FIG. 4 A, in FIG. 4 B the circle center 402 is shownlocated in a different position to the center of the field of viewcenter 406. In FIG. 4 B, the field of view center 406 is shown locatedat coordinates X₀, Y₀, indicated by the intersection point of lines 407and 408, respectively. In FIG. 4 B, the circle center 402 is shownlocated at coordinates X₁, Y₁, indicated by the intersection point ofdashed lines 409 and 410, respectively. When the circle center 402 islocated in a different position as the field of view center 406, thereis a difference between the coordinates of the circle center 402 and thefield of view center 406, thus the absolute value of X₁−X₀>0 and/or theabsolute value of Y₁−Y₀>0.

The processor 308 is configured to execute instructions contained in thenon-transitory computer-readable medium 310 to detect the circle center402 and the field of view center 406. The processor 308 is alsoconfigured to execute instructions contained in the non-transitorycomputer-readable medium 310 to calculate the respective XY coordinatesof the circle center 402 and the field of view center 406, and to detecta difference in the coordinates of the circle center 402 and the fieldof view center 406. Accordingly, upon detecting a difference between thecoordinates of the circle center 402 and the field of view center 406,when the absolute value of X₁−X₀>0 and/or the absolute value of Y₁−Y₀>0,the processor, executing instructions contained in the non-transitorycomputer-readable medium, sends movement instructions to the motorizedmicroscope head support 315 according to the XY plane to reposition thefield of view center 406 at the same location as the circle center 402,to result in the absolute value of X₁−X₀=0 and the absolute value ofY₁−Y₀=0. For example, as shown in FIG. 4 B, upon detecting the positionof the circle center 402 having coordinates different from the field ofview center 406, the processor, executing instructions contained in thenon-transitory computer-readable medium, sends movement instructions tothe motorized microscope head support 315 to relocate the field of viewcenter 406 as depicted as arrows 411 and 412.

The coordinates of the field of view center 406 and the circle center402 may be values calculated relative to the origin, wherein the originis the point of intersection of the X axis and the Y axis of the XYplane. The values may be any suitable units of distance such as mm orμm. The processor is configured to execute instructions contained in thenon-transitory computer-readable medium to calculate the values of thecoordinates in the XY plane, such as values relative to the origin.Accordingly, the values of X and Y coordinates increase with increasingdistance from the origin. Thus, the positions of the field of viewcenter 406 and the circle center 402 can be calculated, and the relativepositions of the field of view center 406 and the circle center 402 inthe XY plane can be calculated relative to the origin. Accordingly, forexample, as shown in FIG. 4 A and FIG. 4 B, when the origin is placedproximally on the left side, the value of X increases from left toright, and the value of Y increases from proximal (back) to distal(forward). Thus, in the exemplary schematic shown in FIG. 4 B, thelocation of the circle center 402 is detected as being to the right andforward (more distal) than the field of view center 406, thus X₁−X₀>0and Y₁−Y₀>0. In contrast, if the circle center 402 is located to theleft and more proximal (back) than the field of view center 406, thenthe coordinates calculated relative to the origin would give X₁−X₀<0 andY₁−Y₀<0. In both cases, when the circle center 402 is in a differentlocation to the field of view center 406, the absolute value of X₁−X₀>0and the absolute value of Y₁−Y₀>0.

Alternatively, for example, the coordinates of the XY plane may becalculated relative to the field of view center 406, so that the XYplane 403 of the field of view is divided into four quadrants divided bylines 407 and 408. Thus, as shown in FIG. 4 A and FIG. 4 B, the top leftquadrant will have positive values of Y and negative values of Xrelative to the field of view center 406, the top right quadrant willhave positive values of Y and positive values of X relative to the fieldof view center 406, the bottom left quadrant will have negative valuesof Y and negative values of X relative to the field of view center 406,and the bottom right quadrant will have negative values of Y andpositive values of X relative to the field of view center 406. Thus,coordinates of a circle center 402 located in a position in any quadrantcan be calculated relative to the field of view center 406.

In implementations described herein, the field of view center 406 maycorrespond to the center of the display 311. Accordingly, uponpositioning the field of view center 406 at the same location as thecircle center 402, the circle center is positioned at the center of thedisplay 311.

The movement instructions sent to the motorized microscope head support315 may have a parameter of velocity, for example measured in anysuitable units such as mm/second or μm/second. For example, the velocityof the movement may be about 1 mm/second. Other velocity values may beused, such as from about 1 μm/second to 1 cm/second. In someimplementations, the value of the velocity may be fixed, whereas inother implementations the value of the velocity may be variable. In someimplementations, the value of the velocity may vary according to therelative positions of the circle center 402 and the field of view center406. For example, as the absolute value of X₁−X₀ and/or the absolutevalue of Y₁−Y₀ increases, the velocity may increase. Accordingly, as theabsolute value of X₁−X₀ and/or the absolute value of Y₁−Y₀ decreases,the velocity may decrease. As depicted in FIG. 4 A and FIG. 4 B,triangles 413 indicate a relationship of increasing velocity of themovement with increasing distance of the circle center 402 from thefield of view center 406. In some implementations, the increase invelocity of movement with increase in distance of the circle center 402from the field of view center 406 may be linear (for example, asdepicted by triangles in FIG. 4 A and FIG. 4 B). In otherimplementations, the increase in velocity of movement with increase indistance of the circle center 402 from the field of view center 406 maybe non-linear. For example, the increase in velocity may follow a curvedfunction wherein the velocity increases by a multiplication factorproportional to the increasing distance between the circle center 402and the field of view center 406.

In a preferred implementation, the movement velocity increases withincreasing distance between the circle center 402 and the field of viewcenter 406 and decreases with decreasing distance between the circlecenter 402 and the field of view center 406. Accordingly, preferably themethod may be implemented, and the system so configured, to result in aslow ramping up and ramping down of the movement velocity withrespective increasing or decreasing distance between the circle center402 and the field of view center 406.

Accordingly, an object of the present invention is automatic computerprocessor-mediated centering in the microscope field of view and thelinked display of the detected circle in the image of the magnified eyewherein the centering has smooth movement. In particular, an object ofthe invention is an automatically controlled response to detecting an‘off-center’ circle image in a magnified eye that smoothly repositionsthe circle in the center of the field of view. The centering occurs inreal-time upon capture and image processing of the live video of themagnified eye during ophthalmic surgery. In some implementations, thesystem is configured so that the velocity of the centering movement maybe set according to user preference.

In some implementations, the absolute value of X₁−X₀ and/or the absolutevalue of Y₁−Y₀ may have a set minimum value before the processor 308sends the movement instruction to the motorized microscope head support315. Accordingly, the system described herein may allow some movement ofthe circle center 402 relative to the field of view center 406 before arepositioning of the microscope field of view is executed. For example,the position of the field of view center 406 may vary from the detectedcircle center 402 by a set distance or a set proportion of the field ofview or the detected circle before the processor 308 sends the movementinstruction to the motorized microscope head support 315. For example,in some implementations, the position of the field of view center 406may vary from the detected circle center 402 by approximately 10% of thediameter of the of the field of view or the detected circle before theprocessor 308 sends the movement instruction to the motorized microscopehead support 315.

In some implementations, the view of the magnified image presented onthe display can be a portion or a subset of the field of view of themicroscope and of the real-time video image. As shown in FIG. 4C, adashed box 414 may indicate the view presented on the screen, whereinthe position of the dashed lines may correspond to the edges of thedisplay screen. Accordingly, one of the objectives of the presentinvention is to maximize the size of the magnified image of the detectedcircular shape on the display screen. In this way, a maximal area of thedisplay screen may be utilized for displaying the magnified image of theeye to the surgeon. In some implementations, the zoom of themagnification can be set by a user, such as the surgeon to maximize thesize of the magnified image of the detected circular shape on thedisplay screen. In other implementations, the processor, executinginstructions contained in the non-transitory computer-readable medium,may detect a diameter of a detected circular image, and control the zoomlevel of the field of view so that the diameter of the detected circularimage is fitted within the edges of the display screen. In someimplementations, the zoom level may be adjusted by the processor,executing instructions contained in the non-transitory computer-readablemedium to send an instruction to the microscope to change the opticalzoom of the microscope accordingly. In other implementations, the zoomlevel may be adjusted by the processor, executing instructions containedin the non-transitory computer-readable medium, to change the digitalzoom of the image that is transmitted to the display accordingly. Inparticular, when the display is rectangular, such as alandscape-oriented screen, e.g. 16×9 aspect ratio OLED screen typicallyused in conjunction with the NGENUITY® system, the zoom level may be setso that the diameter of the detected circular shape is fitted within thevertical extent of the display screen. Accordingly, in someimplementations, on a rectangular screen, the circular image may bepositioned in the center of the display, or to one side leaving room onthe rectangular display such as the exemplary 16×9 display foradditional information, such as pre-operative images and/or electronicmedical records. FIG. 5 shows a schematic 500 of an exemplary circle 501positioned with its center at the center of the vertical extent of anexemplary display 502. The term “centering” as used herein may refer topositioning of the center of a circle on a display, wherein thepositioning is effective to orient the center of the circle at alocation at or near the middle of the screen space of a display orwithin a user-defined or pre-set region thereof. In someimplementations, the term “centering” may refer to the positioning ofthe center of the circle within a set distance of the center of thedisplay, such as within 10% of the center 503 of the display, asindicated by region 504 shown in FIG. 5. In some implementations, adisplay may be square, while in other implementations, the display maybe rectangular. Other display shapes are also possible. With regard to asquare display, the term “center of the display” may refer to a locationthat is approximately equidistant from each of the sides. With regard toa rectangular display, the term “center of the display” may refer to alocation that is approximately equidistant from each of the sides, or inparticular equidistant from each of the long sides 505 of the rectangle,as indicated by location 502 in the exemplary schematic rectangledisplay shown in FIG. 5. In some implementations, the centering may beperformed to preferably result in the positioning of the circle so thatthe entire circle is visible on the display. In other implementations,the centering may be performed to result in the positioning of thecircle so that only a portion of the circle is visible on the display.

In various implementations described herein, detection of the circularimage may use any suitable algorithm identifiable by persons skilled inthe art for detection of circles in images. Standard algorithms that maybe used to detect circles include circle Hough Transform and randomsample consensus (RANSAC), among others identifiably by skilled persons.

The term “Hough transform” as used herein refers to a feature extractiontechnique used in image analysis, computer vision, and digital imageprocessing. The purpose of the technique is to find imperfect instancesof objects within a certain class of shapes by a process termed a votingprocedure. This voting procedure is carried out in a parameter space,from which object candidates are obtained as local maxima in a so-calledaccumulator space that is explicitly constructed by the algorithm forcomputing the Hough transform.

The term “circle Hough Transform” or “CHT” as used herein refers to aspecialization of Hough Transform, and is a basic technique routinelyused in Digital Image Processing, for detecting circular objects in adigital image. The circle Hough Transform (CHT) is a feature extractiontechnique for detecting circles. The purpose of the technique is to findcircles in imperfect image inputs. The circle candidates are produced by“voting” in the Hough parameter space and then select the local maximain a so-called accumulator matrix.

As persons skilled in the art would understand, in a two-dimensionalspace, a circle can be described by:

(x−a)²+(y−b)² =r ²  (Eq. 1)

where (a,b) is the center of the circle, and r is the radius. If a 2Dpoint (x,y) is fixed, then the parameters can be found according toEq. 1. The parameter space would be three dimensional, (a, b, r). Andall the parameters that satisfy (x, y) would lie on the surface of aninverted right-angled cone whose apex is at (x, y, 0). In the 3D space,the circle parameters can be identified by the intersection of manyconic surfaces that are defined by points on the 2D circle. This processcan be divided into two stages. The first stage is fixing radius thenfind the optimal center of circles in a 2D parameter space. The secondstage is to find the optimal radius in a one dimensional parameterspace.

In some implementations, the radius of the circle may be fixed. If theradius is fixed, then the parameter space would be reduced to 2D (theposition of the circle center). For each point (x, y) on the originalcircle, it can define a circle centered at (x, y) with radius Raccording to Eq. 1. The intersection point of all such circles in theparameter space would be corresponding to the center point of theoriginal circle.

For example, 4 points 602 on a circle 601 in an exemplary circle image600 may be considered as shown in FIG. 6. An exemplary circle Houghtransform 700 is shown in FIG. 7. For each (x,y) of the four points 602in the original image 600, the circle Hough transform can define acircle in the Hough parameter space centered at (x, y) with radius r. Anaccumulator matrix is used for tracking the intersection point. In theparameter space, the voting number of points through which the circlepassing would be increased by one. Then the local maxima point 701 (thepoint in the center) can be found. The position (a, b) of the maxima 701would be the center of the original circle 601.

As would be understood by skilled persons, in practice, an accumulatormatrix is introduced to find the intersection point in the parameterspace. First, the parameter space is divided into “buckets” using a gridto produce an accumulator matrix according to the grid. The element inthe accumulator matrix denotes the number of “circles” in the parameterspace that passing through the corresponding grid cell in the parameterspace. The number is also called “voting number”. Initially, everyelement in the matrix is zeros. Then for each “edge” point in theoriginal space, a circle can be formulated in the parameter space andincreases the voting number of the grid cell which the circle passingthrough. This process is called “voting”.

After voting, the local maxima can be found in the accumulator matrix.The positions of the local maxima correspond to the circle center in theoriginal space.

For circles with unknown radius, since the parameter space is 3D, theaccumulator matrix would also be 3D. Possible radii may be iteratedthrough; for each radius, the previous technique is used. Finally, thelocal maxima is found in the 3D accumulator matrix. The accumulatorarray should be A[x,y,r] in the 3D space. Voting should be for eachpixels, radius and theta A[x,y,r]+=1.

As would be understood by skilled persons, an exemplary algorithm is asfollows: (1) For each A[a,b,r]=0; (2) Process the filtering algorithm onimage Gaussian Blurring, convert the image to grayscale (grayScaling),make Canny operator, The Canny operator gives the edges on image. (3)Vote the all possible circles in accumulator. (4) The local maximumvoted circles of Accumulator A gives the circle Hough space. (5) Themaximum voted circle of Accumulator gives the circle.

As would be understood by skilled persons, an exemplary code for thecircle Hough transform voting process is as follows:

For each pixel(x,y) For each radius r = 1Ø to r = 6Ø // the possibleradius For each theta t = Ø to 36Ø // the possible theta Ø to 36Ø a = x− r = cos(t * PI / 180); // polar coordinate for center b = y − r =sin(t * PI / 180); //polar coordinate for center A[a,b,r] +=1; //votingend end end

Other exemplary implementation codes are identifiable by persons skilledin the art, such as those used in MATLAB and Python.

In some implementations, the Hough Circle Detection program may be usedto detect circles in images, which uses the Hough algorithmCvHoughCircles from the OpenCV library, identifiable by skilled persons.In the Hough Circle Detection program, parameters can be defined, suchas minimum radius, maximum radius, and various applicable thresholds andfilters identifiable by skilled persons.

In some implementations, detection of circles in images as performed byOpenCV may use the Hough Gradient method, such as the function in OpenCVreferred to as “cv2.HoughCircles( )”, identifiable by persons skilled inthe art.

Advantages of the method and system described herein include rapid,precise automatic centering of the high magnification video image on thedisplay, allowing continuous use of high magnification while eliminatingthe need for manual control of centering the video image by the surgeon,e.g. via a foot pedal joystick control, which can lead to off the screendisplay or inadvertent hand motion caused by foot pedal joystickactivation.

The above disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other implementations which fall withinthe true spirit and scope of the present disclosure. Thus, to themaximum extent allowed by law, the scope of the present disclosure is tobe determined by the broadest permissible interpretation of thefollowing claims and their equivalents, and shall not be restricted orlimited by the foregoing detailed description.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contentclearly dictates otherwise. The term “plurality” includes two or morereferents unless the content clearly dictates otherwise. Unless definedotherwise, all technical and scientific terms used herein have the samemeaning as commonly understood by one of ordinary skill in the art towhich the disclosure pertains.

1. A system configured for automatically centering in an XY plane afield of view of a patient's eye under high magnification duringophthalmic surgery, the system comprising: a processor; and anon-transitory computer-readable medium accessible to the processorcontaining instructions executable by the processor for: acquiring, froma photosensor, a real-time video signal representing a field of viewcomprising the patient's eye under high magnification by a microscope,wherein the field of view comprises an en-face XY plane; displaying on adisplay at least one view within the field of view corresponding to thereal-time video signal; detecting a circular image in the real-timevideo signal, wherein the circular image comprises a target image in thefield of view; determining the location of the center of the circularshape within the XY plane of the field of view; determining the locationof the center of the field of view in the XY plane; comparing thelocation of the center of the circular image and the location of thecenter of the field of view; upon determining a difference in thelocations of the center of the circular image and the center of thefield of view, transmitting a movement instruction to a motorizedmicroscope support configured to move the location of the microscopefield of view in the XY plane, wherein the movement instruction directsmovement of the microscope field of view to place the center of thefield of view at the location of the center of the circular image;thereby automatically moving the center of the field of view to thecenter of the circular image detected in the real-time video signalacquired from the field of view of the patient's eye under highmagnification during ophthalmic surgery.
 2. The system of claim 1wherein the center of the field of view corresponds to a set location onthe display.
 3. The system of claim 2 wherein the set location on thedisplay is the center of the display.
 4. The system of claim 2 whereinthe display is a rectangular display and the set location on the displayis a location at a mid-point between the long sides of the rectangulardisplay.
 5. The system of claim 1 wherein the circular image correspondsto an illuminated portion of the inside of the patient's eye viewablethrough a pupil of the eye.
 6. The system of claim 1, wherein themovement instructions transmitted to the motorized microscope headsupport comprise a parameter of velocity, wherein the value of thevelocity is variable as a function of distance between the location ofthe center of the field of view and the center of the circular image. 7.The system of claim 6, wherein the value of the velocity of the movementinstructions increases with increasing distance between the location ofthe center of the field of view and the center of the circular image. 8.The system of claim 7, wherein the value of the velocity of the movementinstructions increases linearly.
 9. The system of claim 7, wherein thevalue of the velocity of the movement instructions increasesnon-linearly.
 10. The system of claim 1, wherein: the magnification hasa zoom having a value; and the display has an area; further comprising:detecting, by the processor, executing instructions contained in thenon-transitory computer-readable medium, a diameter of the circularimage; transmitting, by the processor, executing instructions containedin the non-transitory-computer-readable medium, an instruction to adjustthe value of the zoom of the magnification so that the diameter of thedetected circular image is fitted within a maximal portion of the areaof the display; wherein the transmitting of the instruction to adjustthe value of the zoom is selected from (a) transmitting an instructionto the microscope to adjust an optical zoom of the field of view of themicroscope; and (b) transmitting an instruction to the display to adjusta digital zoom of the field of view of the real-time video signal. 11.The system of claim 1, wherein the instructions contained in thenon-transitory computer readable medium executed by the processor forthe detecting of the circular image comprises a circle Hough transformalgorithm.
 12. The system of claim 1 wherein the ophthalmic surgerycomprises a vitreoretinal surgery.
 13. The system of claim 1 wherein thereal-time video signal is a 3D video signal.
 14. The system of claim 1,comprising an NGENUITY® 3D Visualization System.
 15. A method ofautomatically centering in an XY plane a field of view of a patient'seye under high magnification during ophthalmic surgery, comprising thesteps of: acquiring, by a processor executing instructions contained ina non-transitory computer-readable medium, from a photosensor, areal-time video signal representing a field of view comprising thepatient's eye under high magnification by a microscope, wherein thefield of view comprises an en-face XY plane; displaying on a display,via the processor executing instructions contained in the non-transitorycomputer-readable medium, at least one view within the field of viewcorresponding to the real-time video signal; detecting a circular imagein the real-time video signal, by the processor executing instructionscontained in the non-transitory computer-readable medium, wherein thecircular image comprises a target image in the field of view;determining, by the processor executing instructions contained in thenon-transitory computer-readable medium, the location of the center ofthe circular image within the XY plane of the field of view;determining, by the processor executing instructions contained in thenon-transitory computer-readable medium, the location of the center ofthe field of view in the XY plane; comparing, by the processor executinginstructions contained in the non-transitory computer-readable medium,the location of the center of the circular image and the location of thecenter of the field of view; and upon determining a difference in thelocations of the center of the circular image and the center of thefield of view, transmitting, by the processor executing instructionscontained in the non-transitory computer-readable memory, a movementinstruction to a motorized microscope support configured to move thelocation of the microscope field of view in the XY plane, wherein themovement instruction directs movement of the microscope field of view toplace the center of the field of view at the location of the center ofthe circular image; thereby automatically moving the center of the fieldof view to the center of the circular image detected in the real-timevideo signal acquired from the field of view of the patient's eye underhigh magnification during ophthalmic surgery.